hive-udaf开发实例1

1，pom配置：

<dependency>

    <groupId>org.apache.hive</groupId>

    <artifactId>hive-exec</artifactId>

    <version>1.1.0-cdh5.8.3</version>

</dependency>

<dependency>

    <groupId>org.apache.hadoop</groupId>

    <artifactId>hadoop-client</artifactId>

    <version>2.6.0-cdh5.8.3</version>

</dependency>

2,java代码：

package com.ibeifeng.udaf;

import org.apache.hadoop.hive.ql.exec.UDAF;

import org.apache.hadoop.hive.ql.exec.UDAFEvaluator;

public class Wm_concat extends UDAF {

public static class myUDAFEval implements UDAFEvaluator{

private PartialResult partial = new PartialResult();
public static class PartialResult{
String result = "" ;
String delimiter = null;
}
@Override
public void init() {
// TODO Auto-generated method stub
partial.result = "";
}
public  boolean  iterate(String value, String deli){
if (value == null || "null".equalsIgnoreCase(value)) {
return true;
}
if (partial.delimiter == null) {
partial.delimiter = deli;
}
if (partial.result.length() > 0) {
partial.result = partial.result.concat(partial.delimiter);
}
partial.result = partial.result.concat(value);
return true;
}
public  PartialResult  terminatePartial() {
return partial;
}
public  boolean  merge(PartialResult other){
if (other == null) {
return true;
}
if (partial.delimiter == null) {
partial.delimiter = other.delimiter ;
partial.result = other.result ;
}else {
if(partial.result.length() > 0){
partial.result = partial.result.concat(partial.delimiter);
}
partial.result = partial.result.concat(other.result);
}
return true ;
}
public String terminate() {
if (partial == null || partial.result.length() == 0) {
return null;
}
return partial.result ;
}
}

}

3，导出jar包

4，hive中导入jar包
addjar /opt/beifeng/jars/hive_UDF.jar;
createtemporary function Wm_concat as 'com.ibeifeng.udf.GetCmsID ';

5，hive sql使用udf
select getcmsid(url) from info_tab group by id;